Circles

Circles

By Ashley Carson

Circle

The set of points equidistant from a given point called the center

Parts of a Circle

• Radius: line segment that goes from the center to the edge of the circle (HALF the DIAMETER)

• Diameter: line segment that goes from edge to edge on a circle (TWICE the RADIUS)

• Circumference: the distance around the outside of a circle (AKA perimeter)

Multiple Choice

Name the pictured part of the circle.

• Diameter

• Sector

• Radius

• Central Angle

• Arc

Multiple Choice

What is a straight line that goes through the center of a circle from side to opposite side?

• Diameter

• Circumference

• Radius

• Center

Multiple Choice

Does this picture show the diameter or radius of a circle?

• Diameter

• Radius

Multiple Choice

A tire has a radius of 14 inches. What is its diameter?

• 14 inches

• 7 inches

• 28 inches

Fill in the Blank

What is the length of the radius of the circle?

Multiple Choice

A pond has a diameter of 12 feet. What is its radius?

• 12 feet

• 6 feet

• 24 feet

Circumference

• There are two fomulas for finding circumference

• C = πd

• C = 2πr

• Circumference is a little more than 3 times the diameter

What is Pi?

• the ratio of the circumference to the diameter of a circle (π= c/d)

• a greek symbol (π)

• approximately 3.14

• used when solving area and circumference of circles

Multiple Choice

The distance around a circle; much like the perimeter of a rectangle.

• perimeter
• diameter
• circumference
• radius

Multiple Select

What is pi?

Check ALL applicable answers!

• a delicious dessert

• the ratio between circumference and diameter

• a Greek symbol

• exactly 3.14

• approximately 3.14

Circumference

These are the two formulas for finding circumference. They both use a special number called pi.

Fill in the Blank

The radius of the circle is 9 meters. What is the circle's circumference?

Fill in the Blank

A cruise ship has a large, circular window with a diameter of 6 meters. What is the window's circumference?

(Round to the hundredths)